The present invention relates to an electric fan, and more specifically to a lubricating oil leakage preventive arrangement for an electric fan, which prevents a loss of lubricating oil from the lubricating axle bearing.
A variety of miniature electric fans have been disclosed for use in electronic apparatus (for example, computer mainframe, video cassette recorder, copy machine, etc.) to dissipate heat, so as to prevent a damage to electronic parts due to an overheat. FIG. 1A shows a prior art electric fan for this purpose. This structure of electric fan comprises a body, a fan blade assembly, and a lubricating axle bearing. The body comprises a seat at the center, a center shaft disposed at the center of the seat and defining an axially extended center axle hole, a winding and a circuit board mounted in the seat around the center shaft. The fan blade assembly comprises a cup-like hub, a plurality of fixed blades equiangularly and obliquely spaced around the hub, a magnet mounted within the hub, and an axle axially disposed at the center of the hub and coupled to the center axle hole of the center shaft at the body. The lubricating axle bearing is mounted within the axle hole of the center shaft around the axle of the fan blade assembly for releasing lubricating oil upon rotary motion of the axle. This structure of electric fan is still not satisfactory in function. During rotary motion of the axle in the lubricating axle bearing, a centrifugal force is produced, and lubricating oil tends to be forced out of the axle bearing and the shaft by the centrifugal force (see FIG. 1B). Therefore, lubricating oil reduces quickly with the use of the electric fan. Insufficient application of lubricating oil to the contact area between the axle and the lubricating axle bearing causes the axle to wear quickly, and a high noise will be produced during rotary motion of the axle.